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1

Digitale Medien

One-Bond 13C, 13C-Spin Coupling in η4-, η3- and η2-Olefin Transition Metal Complexes13C-NMR. Spectroscopy, Part XXXI; Part XXX: [1]. (1981)

Zobl-Ruh, Susanne ; von Philipsborn, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 64 (1981), S. 2378-2382

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: One-bond 13C, 13C-spin-coupling constants have been measured, with natural isotope abundance, in η4-diene, η3-allyl and η2-ene transition-metal carbonyl complexes. Typical values of 1J(C,C) are given for Fe-, Ru- and Os-complexes with the three types of olefinic ligands. The effects of substituents and the structural significance of the C,C-coupling constants are discussed.

Zusätzliches Material: 4 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19810640744

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2

Digitale Medien

New Synthetic Routes to β-Olefinic Trialkoxyphosphonium Salts and Phosphonates: Organometallic Variants of the Michaelis-Arbuzov ReactionReactions with Metal-Coordinated Olefins, Part V. Part IV: see [1]. Presented in part at the XIIth International Conference on Organometallic Chemistry, Vienna, September 1985. (1986)

Hafner, Andreas ; Von Philipsborn, Wolfgang ; Salzer, Albrecht

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 1757-1767

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The low-temperature addition of tertiary phosphites to [(allyl)Fe (CO)4]+X- complexes proceeds regio- and stereospecifically and produces metal-coordinated β-olefinic trialkoxyphosphonium ions. These can be converted by various routes into the uncomplexed phosphonium salts or phosphonates. Similar reactions of acyclic [(dienyl)Fe(CO)3]+X- compounds give metal-coordinated (2,4-dien-1-yl)trialkoxyphosphonium salts or dialkyl (2,4-dien-1-yl)phosphonates. The mechanisms and their relationship to the classical Michaelis-Arbuzov reaction are discussed. The new compounds are characterized, if possible, by 1H-, 13C-, and 31P-NMR spectra. The new phosphonium salts and phosphonates, potentially useful for Wittig-Horner reactions, are difficult to obtain by conventional routes.

Zusätzliches Material: 3 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690733

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3

Digitale Medien

Synthesis and 1H-, 13C-, and 57Fe-NMR spectra of mono- and bis[tricarbonyl(η4-diene)iron], and (η3-allyl)tetracarbonyliron trifluoroborate complexesTransition-Metal NMR Spectroscopy, Part XI. Part X: [1]. (1988)

Adams, Christoph M. ; Cerioni, Giovanni ; Hafner, Andreas ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 71 (1988), S. 1116-1142

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: A variety of mono- and bis[Fe(CO)3(η4-diene)] complex with alky, CH2OH, CHO, COCH3, COOR, and CN substituents on the 1,3-diene system have been synthesized. Dienes with a (Z)-configuration terminal Me group show steric inhibition of metal complexation resulting in lower yields and formation of tetracarbonyl(η2-diene) and tricarbonyl(η4-heterodiene) complexes as additional products. Regioselective attack by C-nucleophiles at the carbonyl C-atoms of the functional group with or without concomitant 1,3 mogration of the Fe(CO)3 group was used to synthesize polyenes and isoprenoid building blocks as mono- or dinucliar Fe(CO)3 complexes. Wittig-Horner-type reactions of Fe(co)3-complexed synthons result in sterospecific formation of (E)-configurated olefins. The 1H-, 13C- and 57Fe-NMR spectra of olefinic and allylic organoiron complexes are reported, H,H,C,H, and C,C coupling constants have been evaluated and are analyzed in terms of the geometry of the coordinated diene. The results are corroborated by the crystal structure of tricarbonyl[3-6-η-((E)-6-methyl-3,5-heptadiene-2-one)]iron(34) which shows an unusual distortion of the (CH3)2C = group, The 57Fe-NMR chemical shifts extend over the ranges of 0-600 ppm for [Fe(CO)3(η4-diene)] complexes, 780-1710 ppm for [Fe(CO)4(η3-allyl)] [BF4] and [FeX(CO)3(η4-allyl)] complexes, and 1270-1690 ppm for [Fe(CO)3(η4-enone)] complexes, relative to Fe(CO)5.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19880710526

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4

Digitale Medien

13C-NMR. Spectra, Structure and Reactivity of Cyclic Oxocarbons13C-NMR. Spectroscopy, Part XVII; for Part XVI see [1].In memory of the late Prof. Hans Schmid (1977)

Städeli, Werner ; Hollenstein, Roger ; Von Philipsborn, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 60 (1977), S. 948-958

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The structures of cyclic polyketones, their hydrates and reduction products were studied in different solvents by 13C-NMR. spectroscopy. In dimethylsulfoxide solution rhodizonic acid (1), croconic acid (2) and squaric acid (3) exhibit signal averaging. In anhydrous tetrahydrofuran 1 and 2 could be observed as non-dynamic species. The spontaneous reactions of dodecahydroxycyclohexane (5) and decahydroxycyclopentane (‘leuconic acid’) (6) and the sequence of formation of ring-contracted products were investigated. Key intermediates could be clearly identified which support the mechanism proposed earlier involving a benzylic acid type rearrangement followed by decarboxylation and subsequent redox reactions.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19770600325

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5

Digitale Medien

n-π-Interaction in Enamines and Enaminoketones. A 15N-NMR. Study15N-NMR. Spectroscopy, Part III; Part II [1]. (1977)

Schwotzer, Willi ; Von Philipsborn, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 60 (1977), S. 1501-1509

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: 15N-Chemical shifts of 32 enamines, 11 enaminoketones and 28 closely related amines have been determined with the isotope in natural abundance. In order to eliminate substituent effects, differential chemical shifts Δδ(N) are defined as δN(amine)-δN(enamine). This parameter is shown to correlate well with the free enthalpy of activation ΔG# for restricted rotation about the N—C(α) bond in enamines with extended conjugation. Δδ(N) values of substituted anilinostyrenes correlate also with 13C-chemical shifts of the β-carbon in the enamine system and with Hammett σ-constants of the aniline substituents. The experimental results suggest that differential 15N shifts are a useful probe to study n, π-interaction in enamines.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19770600507

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6

Digitale Medien

Conformational Dependence of One-Bond Cα,H Spin Coupling in Cyclic Peptides13C-NMR, Spectroscopy, Part XXIX; part XXVIII see [1].Dedicated to Prof. Conrad Hans Eugster on the occasion of his 60th birthday (1981)

Egli, Huldrych ; Von Philipsborn, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 64 (1981), S. 976-988

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Conformational effects on the one-bond Cα, H coupling constant have been studied in cyclic oligopeptides containing glycine, alanine, sarcosine and proline. The conformational contribution to 1J (Cα, H) can be described as being composed of a positive hyperconjugative term from the neighbouring N-pz orbital and a negative one from the carbonyl π-system. For glycyl units, a quantitative relation between 1J (Cα,H) and the vicinal interorbital angles Φ′ and Ψ′ is derived with maximum values ΔJ (Ψ′) = + 14.0 Hz and ΔJ (Ψ′) = -4.9 Hz. Applications to conformational analysis of cyclo (L-Pro-Gly)3, cyclo (D-Ala-D-Ala-L-Ala-D-Ala-L-Ala-L-Ala) and cyclo (Sar)8 are presented.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19810640404

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7

Digitale Medien

Direct Observation of 103Rh-Chemical Shifts in Mono- and Dinuclear Olefin ComplexesTransition Metal NMR. Spectroscopy, Part III; Part II see [1]. (1982)

Maurer, Ellen ; Rieker, Susanne ; Schollbach, Michael ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 65 (1982), S. 26-45

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The 103Rh-resonance has been investigated at 2.8 MHz in mono- and dinuclear olefin complexes by steady-state NMR.-pulse techniques. For dirhodium complexes with scalar Rh, Rh-coupling, a selective rf-irradiation was applied to improve sensitivity. Within the same measuring time the signal/noise ratio is improved by the factor (T2/T2*)1/2 by this steady-state method in comparison with the usual free-induction technique. (T1/T2)-ratios, as obtained from the dependence of signal in tensity on the pulse-flip angle are discussed in terms of relaxation mechanisms and chemical exchange phenomena. From (T1/T2)- and (T1 + T2)-experiments, individual T1 and T2 values have been determined for C5H5RhC8H12 and Rh(acac)3.The 103Rh-chemical shifts of 39 olefin complexes are reported. Shielding depends upon the (formal) oxidation state of Rh whereby resonances of pure olefin complexes appear at the low-frequency end of the δ-scale, which extends over 10000 ppm. For cyclic 1,3-diene ligands Rh-shielding increases with decreasing ring size and decreases with further conjugation of the diene systems.In the dirhodium complexes, Rh, Rh spin-coupling constants are 〈 10 Hz. Rh, C-coupling constants in (diene)RhCp-complexes increase, for the terminal diene C-at om, with increasing ring size of the 1,3-diene, 1J(Rh, C) = 11.7 to 17.4 Hz.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19820650105

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8

Digitale Medien

Dimetallic Complexes with Bridging Seven-membered Cycloolefins. Synthesis, Multinuclear NMR.-Spectroscopic Properties and StructureReactivity of Complexed Carbocycles, Part XIV; Part XIII see [1]; Transition Metal NMR. Spectroscopy Part IV; Part III see [2]. (1982)

Salzer, Albrecht ; Egolf, Thomas ; Von Philipsborn, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 65 (1982), S. 1145-1157

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The synthesis of dimetallic olefin complexes of the type L1M1C7H7M2L2 (M1 = Fe, Co, Rh; M2 = Rh, Ir, Pd; L1 = CO, C5H5; L2 = diene, allyl, P(OR)3) is described. The fluxional structures were investigated by 13C-, 57Fe- and 103Rh-NMR.-spectroscopy, and a cisoid dimetallic coordination, including a (metal, metal)-bond, can be deduced for the C7H7-ring. 57Fe- and 103Rh-chemical shifts give indications for the charge distribution in the 34e-complexes. The homodimetallic complex (Cp)Rh(tropone)Rh(Cp) (13, Cp = cyclopentadienyl) and the corresponding 2-methoxytropone complex 14 were synthesized in addition to the above mentioned complexes. A fluxional bis(1-3-η-allyl)-coordination of the two Rh-atoms was derived from the temperature-dependent 13C-NMR.-spectra. A spin simulation of the (Cp)-multiplets of 12 and 13 yields information about (Rh, Rh)-spin-coupling which amounts to ≈5 Hz at 30°.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19820650404

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9

Digitale Medien

Solvent-Induced Deuterium Isotope Effects in 13C- and 15N-NMR. Spectra of Enaminones15N-NMR. Spectorscopy, Part IX; Part VIII: [1]. (1982)

Kozerski, Lech ; von Philipsborn, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 65 (1982), S. 2077-2087

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The effect of deuterium on the 13C and 15N chemical shifts of enaminones has been investigated. D/H isotope shifts are reported for neutral and protonated species, i.e., when the isotope is exchanged on the C(2)-, N-, or O-atoms. In cases of slow exchange the isotope shifts were obtained from solutions containing both isotopomers, whereas for fast exchange (acidic solutions) either separate NMR. sample tubes (15N-NMR.) or coaxial tubes (13C-NMR.) were used.In neutral molecules the isotope effects δC(D, H) are intrinsic in nature. In acidic solutions, the enaminocarbonyl cations formed exhibit δC(D, H)- and δN(D, H)-values which are discussed in terms of the proton transfer. The mesomeric character of the cations is reflected by characteristic features in the δC(D, H)- and δN(D, H)-values, which can be ascribed to isotopic perturbation of resonance.O-Protonation shifts in the 15N-resonance, observed for the first time, are large and positive (+60 to +76 ppm), in contrast to amides, where the effects are of the same sign but an order of magnitude smaller. Both protonation shifts and solvent-induced isotope effects are discussed in connection with the nucleophilic character of the reactive centers in the enaminone synthon.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19820650715

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10

Digitale Medien

Simultaneous Formation of 8H-Isoquino[2,1-b][2,7]naphthyridin-8-ones and 13H-Pyrido[4′,3′:3,4]pyrrolo[2,1-b][3]benzazepin-13-ones, a Novel Potential Alkaloidal System (1994)

Nagarajan, Kuppuswamy ; Rodrigues, Patrick J. ; Nethaji, Munirathinam ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 77 (1994), S. 155-163

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Condensation of 3,4-dihydro-6,7-dimethoxyisoquinoline (4) with 4-methylnicotinoyl chloride (12) in refluxing pyridine gives 5,6,13,13a-tetrahydro-2,3-dimethoxy-8H-isoquino[2,1-b][2,7] naphthyridin-8-one (11), along with some of its 13,13a-didehydro derivative 7. A similar reaction of 4 with 4-(chloromethyl)nicotinoyl chloride (14) affords, in addition to 7, the isomeric product 10,11-dihydro-7,8-dimethoxy-13H-pyrido[4′,3′:3,4]pyrrolo[2,1- b][3]benzazepin-13-one (3). Analogous pairs of products are obtained from 3,4-dihydro-6,7-(methylenedioxy)- and 3,4-dihydro-6,7,8-trimethoxy-isoquinolines (15 and 18, resp.). The structure of 3 was established by extensive NMR data and confirmed by single-crystal X-ray studies. Structure 7 has the ring system of the Alangium alkaloids like alangimarinc (1), while the isomeric ring system 3 is predicted to be present in nature on biogenetic reasoning.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19940770118

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